You can show the importance of the direction of a vector by the following
simple experiment.
Get two strong men to pull on the ends of a rope (Figure 1). Now
get a small child to push downwards on the centre of the rope (Figure 2).
It is quite easy to push
the rope downwards because of the directions of all the forces. The men are pulling
horizontally and when the rope is pushed down a little, only a very small fraction of their 'pull'
is trying to prevent the rope from going downwards.
The further down the centre of
the rope is pushed the harder it becomes to push it further. Can you explain why?